Electrically-controlled switch.



H. E. WHITE.

ELEGTRIGALLY CONTROLLED SWITCH.

APPLICATION FILED JULY 15, 1912,

1,1 10,021, Patented Sept. 8, 1914 Fig. 2.

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UNITED s ATEs HAROLD E. WHITE, 01 GLEN RIDGE, NEW JERSEY, ASSIGNOR TGENERAL ELECTRIC PATENT OFFICE.

COMPANY, A CORPORATION OF NEW YORK.

ELECTRICALLY-CONTROLLED SWITCH.

Specification of Letters Patent.

Patented Sept. 8, 1914.

Application filed July 15, 1912. Serial No. 709,498.

sey, have invented certain new and useful Improvements inElectrically-Controlled Switches, of which the followingis aspecification.

This invention provision of a device of this character which willoperate under relatively high current and at the same time be simple inconstruction and efficient in operation.

,"My invention relates more specifically to electromagnetic relays andmore particularly to the type knownas series relays employed in motorstarting apparatus, These relays carry the motor current and arefrequently used to regulate the starting of electric motors, In somecases the current handled is very large, as for instance, 2000 amperesor more and with such a current it is often I difficult to obtain asmall enough excitation for the particular use to which the relay isput.. In many cases a'small fraction of a turn of a-conductor is agreatdeal more than is necessary; i

One of the objeets'of my invention isto provide a relay of thischaracter in which eral application, I have found it particu-' llarlyuseful in connection with motor starting apparatus 1n which a serles ofswitches are arranged to operate progressively to cut out sections ofresistance to bring themotor up to speed. These switches or contactors.havebeen constructed in a great many ways and have been arranged invarious systems which include a series relay to retard the progressionof the switches.

One arrangement which has been used very successfully is described andclaimed in my Patent No. 969,738, September 6, 1910, and

/ also in patent issued to myself and E. R.

Oarichofli', No. 969,585, September 6, 1910.

In the arrangement described in these patents .a series relay isassociated w1th each I contactor, the arrangement being such that therelay is mechanically supported mopen position whenthe contactor isopen. When the contactor closes the mechanlcal support relates toelectrically con-i trolled switches and has for its object the isremoved so. as to permit the relay to close when the current falls to apredetermined value. My present invention is particularly 'appllcable toa relayused in this manner, although it is in no sense limited to thisapplication.

Other objects. of my invention will appear in the course of thefollowing specification 'in which I have shown my invention embodied inillustration. In the accompanying drawings illustratmg my mvention,Figure 1 is a side view of a contactor shown in connection with myimproved relay; Fig. 2 is a front view of 1 the same; Fig. 3 shows adetail of the energizing element; and Fig. 4 is adiagram'of a iysitergin which my invention may be em- 0 1e Refering first to Fig. 4:, inwhich Ihave shown the relay in one of its many uses, it

will be seen that in this system there are two contactors 10 and. 11having associated with them the overload relays 12 and 13.

The core of each relay is supported in its open positionby aprojection.or tail on the contactor arm. The core of the relay 12 00- operateswith an energizing element which ordinarily would be a winding of heavycopper. Where the current is very heavy, as in the present instance,this winding would make the excitation so high that the core wouldnot'drop out at the proper current value. In order to overcome thisdifliculty I employ instead of a winding, a strip of metal, preferablycopper, as shown in Fig.

3. This strip is provided with a perforation 14 through which the cometthe relay 12 moves and at opposite ends is provided with terminals 15and 16, respectively. Opposite the'fperforation 14 is a projection 17having a circuit terminal 18. i

It will be seen froman inspection of Fig.

3 that when current passes between terminals 15 and 16 it divides aroundthe perforation 14: as shown in broken lines and when a circuitconnection is made at 18 instead of at 16 the path of the current willbe changed as shown in dotted lines. This arrangement may be employed invarious ways to bring about the variation in the pull upon the core whenthe circuit connections are changed.

If, for example, the core operates in a magnetic frame, such, forinstance, as the frame .12 (Fig. 1) then when the current passesconcrete form for purposes of between the terminals 15 and 16 the pullupon the core will be determined almost exactly by the current in thebranch conductor threading the magnetic circuit formed by the magneticframe and the core, 2'. e. by the current passing through the branchwhich is to the rear or on the opposite side of the perforation 11 fromthe terminal 18. If now the current passes between terminals 15 and 18instead of between 15 and 16, then the percentage of current passingthrough the rear branch will be decreased and the pull on the coregreatly reduced. On the other hand, in the absence of the magneticframe, as for instance where the frame 12 is made of non-magneticmaterial, the excitation due to each branch circuit will be equal andopposite to that of the other branch so that the core will beunaffected. If, however, under these conditions the current passesbetween terminals 15 and 18 one of the branch circuits will beconsiderably longer than the other so as to have a greater magnetizingeffect and the excitation which affects the core will be thedifferential of the effects produced in the two paths.

In the present case I employ an arrangement in which the magnetic frameis used. In Figs. 1 and 2 is shown a contactor employing such a relay.The particular construction of this contactor forms no part of myinvention and for purposes of illustration I have shown the contactor ofthe type shown in my Patent No. 969,738, above referred to. Energizingthe coil 10 actuates the switch arm 19 pivoted at 20, the contacts 21being located in the arc chute 22. The switch arm is provided with aprojection 23 which engages with the stem 21 of the core of the relay 12to hold it in raised position when the switch is moved to openposit-ion. The iron frame 12 is secured to the contactor frame and theconducting strip through which the core 12 passes is secured to the ironframe by a bolt 18. It will be seen from an inspection of Fig. 4 thatintermediate terminal 18 of Fig. 3 is connected with the contact arm 19through conductor 25.

The operation of my device will be clearly understood from a descriptionof the operation of the system shown in Fig. 4:. Referring to thisfigure, A represents the armature and S the series field of an electricmotor. 26 and 27 are line contactors both of which have windings in acontrol circuit. R, R and R represent sections of resistance and C themaster controller. hen the controller is moved to the first position thecontactor 26 will be closed so that current passes from the positiveside of the line through the contactor 26, armature A, wire 28, throughthe conducting strips of the cores of relays 13 and 12, through theresistances R, It and R series field S and back to the negative side ofthe line. It will be noted that the current passes between the terminals15 and 16 of the energizing elements of the relays and that thereforethe magnetic pull upon the cores is a maximum. If now the controller Cis moved to the second position, the winding of the contactor 10 isenergized so as to bring the contact arm 19 to closed position. Thisremoves the mechanical support from the core of relay 12, but since thepull upon the core is a maximum, the holding up of the core until theincrease of current due to short circuiting the resistance R has takenplace is assured. hen, however, the contactor is closed and theresistance section R cut out, the holding effect upon the coredecreases, since by the short circuiting of the resistance R the currentnow passes from the terminal 15 to the terminal 18. The core is nowmagnetically supported, since there is a rush of current due to thecutting out of resistance section When the current falls to apredetermined value due to the speeding up of the motor, the core willdrop so as to energize the next contactor. This contactor will close soas to short circuit a section of resistance R and change the connectionsof the relay in the same manner as that described in connection with0011- tactor 10. hen the current drops to a predetermined value the coreof the relay 13 of contactor 11 will drop so as to energize thecontactor 27 which will short circuit the resistance R to connect themotor across the line. From this it will be seen that although thecurrent which is taken by the motor may be exceedingly high the actualexcitation of the relay at the time when it is responsive to motorcurrent conditions may be exceedingly small.

While I have described my invention as embodied in concrete form forpurposes of illustration, and as operating in a particular manner, inaccordance with the patent statutes, it should be understood that I donot limit my invention thereto, since various modifications thereof willsuggest themselves to those skilled in the art without departing fromthe spirit of my invention, the scope of which is set forth in theannexed claims.

that I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. An electromagnetic relay comprising a core, an energizing elementtherefor consisting of a conducting strip having a perforation throughwhich the core moves, circuit connections to said strip whereby twobranch circuits are formed around the perforation, and means forchanging the path for the branch circuits so as to change the effectthereof upon the core.

2. An electromagnetic relay comprising a core, an energizing elementtherefor consisting of a conducting strip having a pair of circuitterminals and a perforation for 'said core between the terminals and inalinement therewith, a third terminal out of alinement, and means forchanging connections from one of said terminals to said third terminal.

3. An electromagnetic relay comprising a core, an energizing elementtherefor consisting of an elongated conducting strip having a circuitterminal at each end and a perforation for the core intermediate theterminals and in alinement therewith, a projection'on said stripopposite the perforation provided with a third circuit terminal, andmeans for changing the connections from one of said terminals to saidthird terminal.

4:. An electromagnetic relay comprising an electro-magnet having a coreand an energizing element therefor, said element consisting of aconducting strip having a perforation through which the core moves,circuit connections to said strip whereby two branch circuits are formedaround the perforation one of which is effective u on the core and theother substantially ine ective, and means for changing the path for thebranch circuits so as to vary the effect upon the core.

5. An electromagnetic relay comprising an electromagnet having a coreand an energizing element therefor, said element consisting of aconducting strip having a perforation through which the core moves,circuit connections to said strip whereby two branch circuits are formedaround the perforation one of which is effective on the core and theother substantially ineffective, and means for changing the path for thebranch circuits so as to decrease the effect of the effective branchcircuit.

6. An electromagnetic relay comprising an electromagnet having a coreprovided with a contact member, an energizing element for said coreconsisting of a conducting strip having a perforation therethrough,circuit terminals at opposite sides of said perforation symmetricallyarranged so that the current in flowing between the terminals dividesinto two branches around the per foration one of which is effectivewhile the other is substantially ineffective upon the core, a thirdterminal located out of line with said terminals and perforation, andmeans for changing connections from one of said terminals to said thirdterminal.

In witness whereof, I have hereunto set my hand this twelfth day ofJuly, 1912.

HAROLD E. WHITE.

Witnesses:

E. H. WARING, E. C. JoNEs.

copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. C.

